Incidents relating to the inadvertent firing of firearms are numerous. Frequently, firearms are discharged while being cleaned or by children playing with the weapons. Occasionally, such weapons are also fired during the heat of an argument when rational thinking processes are impaired. There are also problems with the theft of firearms and their subsequent use in the commission of crimes.
Consequently, there is the need for a safety lock for firearms which will effectively preclude the inadvertent or unauthorized use of such weapons. On the other hand, any such safety lock must be easily and quickly released so that the weapon can be used in emergency situations.
The use of safeties or interlocks on firearms is well known and there are numerous prior art documents disclosing both mechanical and electro-mechanical interlocks. Thus, for example, the Schultz U.S. Pat. No. 4,141,166 discloses a safety mechanism for sensing the engagement of a rifle butt with an operator's shoulder and for sensing engagement of the operator's hand with the firearm stock. The sensing switches energize the solenoid which thereupon removes an interposed mechanical member. Purely mechanical interlocks are depicted in the following U.S. Pat. Nos.: Tambour--834,772 (hand grip safety); Gile--1,210,459 (rifle butt stock safety); Lepp--2,041,661 (rifle butt stock satety); Young--2,553,995 (finger-operated safety interlock); Pomeroy--1,484,671 (combination pistol magazine and special trigger safety interlock); Hempstead--1,063,921 (rifle butt stock and trigger guard safety interlock); and Atchisson--3,964,366 (trigger guard safety mechanism).
It is also known to use sequentially activated, push-button locks of both the mechanical and of the electrical type. An example of such lock of the electronic push-button type is disclosed in the U.S. Pat. No. 3,831,065 to Martin et al. The electronic lock disclosed therein is used in a door lock, but it is also known to use such a combination lock in a car ignition.
The foregoing U.S. patents are incorporated by reference in their entirety.